Conventionally, in pharmaceutical, health food, food and other chemical industrial fields, it is widely known that a cellulose powder is used as an excipient to prepare into a molded body containing an active ingredient, for example, a tablet and the like. Particularly, an orally disintegrating tablet that can be taken without water becomes mainstream in recent tablets, and is a dosage form greatly developed in the pharmaceutical formulation field. Recently, an orally disintegrating tablet is manufactured also by the same preparation method as ordinary tablets that is not a special preparation method, but it is originally based on the technologies established by making full use of the compounding ratio of various kinds of additives and excipients, in order to obtain practical tablet hardness and satisfactory disintegration properties and ingestion feel as an orally disintegrating tablet. The formulation based on such technologies is being important as a high value-added formulation, also in product life cycle management (PLCM) of a product, in addition to improvement in quality of life (QOL) to patients. Furthermore, amid the rapid aging of society, an orally disintegrating tablet that is rapidly disintegrated with saliva or a small amount of water greatly contributes to improvement of adherence and compliance, such as convenience in a medical site and ingestability to patients, as a dosage form easily taken even for a patient with low swallowing ability, such as aged people or little children. However, the history of orally disintegrating tablets is short, and there are also technical problems such as the disintegration time and ingestion feel in the oral cavity, and securing of tablet hardness that does not break or wear during manufacture or distribution. Among them, as to ingestion feel, there are many cases that roughness and dryness of powder in which a patient feels when disintegrating a tablet only with the saliva in the oral cavity remain as sense of incongruity, thus satisfactory ingestion feel is not obtained.
Accordingly, development of a technology for manufacturing an orally disintegrating tablet having proper hardness, rapid disintegration properties, and satisfactory ingestion feel without feeling roughness and dryness is desired, and a more highly complete orally disintegrating tablet is expected.
Patent Document 1 describes a cellulose powder with improved compression moldability and liquid component retentiveness by controlling powder physical properties of cellulose powder in a specific range. By using the cellulose powder, it is possible to prepare tablets with high hardness at a low tableting compression force when tableting, and suppress oozing of liquid component from the tablet surface, and it also contributes to prevent tableting troubles. Particularly, powder physical properties are controlled in specific ranges of an average polymerization degree of 150 to 450, an average particle diameter of 30 to 250 μm, and an apparent specific volume of more than 7 cm3/g, and a retention rate of polyethylene glycol with a molecular weight of 400 of 190% or more. However, it is not mentioned at all for disintegration properties and ingestion feel as an orally disintegrating tablet.
Patent Document 2 describes a cellulose crystallite aggregate with an average level-off polymerization degree of 15 to 375, an apparent specific volume of 1.84 to 8.92 cm3/g (apparent density of 7 to 34 lb/ft3), and a particle size of 300 μm or less.
Patent Document 3 describes a pharmaceutical composition consisting of a cellulose powder with an average polymerization degree of 75 to 375 and an apparent specific volume of 1.6 to 3.1 cc/g, containing 2 to 80% by weight of 200 mesh or more components, medicinal ingredients, and other additives.
Patent Document 4 describes a cellulose powder with an average polymerization degree of 150 to 450, an average L/D of particles of 75 μm or less of 2.0 to 4.5, an average particle diameter of 20 to 250 μm, an apparent specific volume of 4.0 to 7.0 cm3/g, an apparent tapping specific volume of 2.4 to 4.5 cm3/g, and an angle of repose of 550 or less.
The cellulose powders obtained by the methods disclosed in Patent Documents 2 to 4 have low compression moldability, thus have a problem that moldability of tablet is insufficient and practical tablet hardness may not be obtained, and it is not mentioned at all for disintegration properties and ingestion feel as an orally disintegrating tablet.